ACV = Diarrhea?

The only new thing I introduced to the quail chicks (2 weeks old) is Apple Cider Vinegar in their water (1 TBSP per quart). Since then, the chicks have brown wet pee... They still have the solid poos but they also have brown pee/poo like diarrhea.

There are a lot of ways to describe poop a picture would be more helpful. Did you only notice a change after adding the vinegar? Their feces does change a bit as time goes on, although it should be mostly moist and not really wet.